A flywheel system and its operator interface are described. Measurements of magnetic bearing negative stiffness are performed. Two digital magnetic bearing control algorithms (PD and estimator based) are defined and their implementations are described. Tuning of each controller is discussed. Comparison of the two controllers' stability, damping noise, and operating current are described. Results describing the superiority of the estimator-based controller are presented and discussed. Dever, Timothy P. and Brown, Gerald V. and Jansen, Ralph H. Glenn Research Center NASA/TM-2002-211795, NAS 1.15:211795, IECEC-2002-20161, E-13490...